This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall purpose of this study is to test the effectiveness of 12 months of increased food intake to improve bone health and restore menstrual cycles in women with menstrual disturbances who exercise regularly and exhibit chronic energy deficiency. We will determine the following: 1) if an increased caloric intake intervention that results in an energy surplus and weight gain in women with Exerciseassociated menstrual disturbances (EAMD) and low to normal bone mineral density (BMD) reverses the deleterious effects of food restriction and negative energy balance on bone outcomes;2) the relative contributions of estrogen-dependent and estrogen-independent pathways to bone outcomes;3) if any improved effects of estrogen status or markers of bone resorption or formation translate into detectable changes in improved bone outcomes, as assessed by serial dual energy x-ray absorptiometry (DXA) and pQCT measurements, that may impact fracture risk;and 4) the relative contribution of changes in body weight, body fat and lean mass to BMD and resumption of menses.